Docs: Standardize C API documentation pages for QkBitTerm, QkExitCode, and QkNeighbors

[ferasshita]

Summary

Standardize and improve formatting in C API documentation pages under docs/cdoc/:

• Fix grammar in qk-bit-term.rst (“An enum that to represent…” → “An enum that represents…”)
• Make "Functions" heading level consistent in qk-neighbors.rst
• Add missing "Functions" section to qk-exit-code.rst

Details and comments

• Only documentation files were changed.
• All changes follow the guidelines for documentation consistency and accessibility.
• No behavioral changes to code or API.
• AI tool used: Microsoft Copilot Chat with GPT-4

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[Copilot]

Pull request overview

This PR standardizes formatting across several C API documentation pages under docs/cdoc/, primarily by fixing grammar and aligning section structure/headings for consistency in the generated Sphinx docs.

Changes:

• Fix grammar in qk-bit-term.rst (“An enum that to represent…” → “An enum that represents…”).
• Adjust the Functions heading adornment in qk-neighbors.rst.
• Add a Functions section header to qk-exit-code.rst.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docs/cdoc/qk-neighbors.rst	Changes the Functions heading underline style for consistency.
docs/cdoc/qk-exit-code.rst	Adds a Functions section header after the enum values list.
docs/cdoc/qk-bit-term.rst	Fixes a grammar issue in the enum description sentence.

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